Joint or seam tracking laser cameras are usually designed with a triangulation laser looking ahead at a fixed distance in front of a process tool attached to a robot. In order to track a joint or an edge or any shape during processing, the cameras are equipped with tracking lasers having sufficient power to provide good signal-to-noise ratio in presence of perturbations by light radiation resulting from welding plasma in electric arc or laser welding, or by welding fumes and spatters or by laser reflection on metallic joints of complex geometry. Such tracking lasers are usually of class 3B type (or IIIb, USA FDA 21 CFR, Ch. 1, sect. 1040.10), which is not safe for human eyes according to IEC 60825-1 standard. For high power laser welding, safety restrictions and measures must be enforced.
Known in the art is US patent application No. 2013/0341312 (Kessler et al.) showing a welding tool with a housing enclosing a fiber laser system. A particular switching element provided on the housing switches a power supply of the fiber laser on when an exit slit is sitting on one of the workpieces and thus activates the fiber laser in that position.
When adjusting and programming robots equipped with tracking laser cameras, operators must wear special protective eyewear. Operators often complain about using unpleasant protective eyewear that prevent clear vision of the working environment. In some plants, other workers in addition to the robot operators must be present at the same place and time during robot programming that may take considerable time. It would be desirable to ease the safety restrictions and allow free vision during robot teaching adjustments.